The invention relates generally to electrical machines and in particular, to a system and method for inserting ripple springs into electrical machines.
Generally, an electrical machine such as power generator or motor is routinely monitored for proper maintenance and high efficiency during operation. One of the few aspects of monitoring health of the electrical machine is inspecting stator bar windings to ensure the windings are motionless during operation of the electrical machine. Typically, an electrical machine includes a wedge system to induce a radial retaining force to a stator to facilitate reducing movement of the stator bar windings within a stator slot. Such a wedge system may also include ripple springs (e.g., top and side ripple springs) embedded in the stator winding assembly. The ripple springs are generally in a state of compression to keep the windings from moving. However, if the wedge system becomes loose, the amount of retaining force is reduced such that the stator bar windings may move during operation. Over time, the relative motion of the stator bar windings causes damage to the insulation surrounding the stator bars and a potential stator bar winding failure can occur. This may result in electrical shorts to ground, thereby, diminishing the efficiency of the machine and further decreasing the mean time between failures of the electrical machines. Accordingly, monitoring the health of the electrical machine is periodically carried out to determine if any stator bar winding movement within the stator slots exceeds predetermined tolerances.
If the wedge system (including the ripple springs) needs to be replaced, then a technician must manually remove and install a new wedge system. To reduce outage time during a maintenance event, it may be desired to leave the rotor in place. When the rotor is left in place, ripple springs can be extremely difficult to install, especially side ripple springs, because the resulting clearances lead to insufficient room for the technician to maneuver and perform the designated task. Typically, a technician would swing a mallet to drive the ripple springs into place. The clearance between the rotor and stator may only be 12 to 24 inches, and this space is too constrained for the technician to effectively swing the mallet and drive the ripple spring into the correct location.
Therefore, to replace the wedge system while the rotor is left in place, there is a continuing need for a more efficient system and method that enables a technician to replace ripple springs.